/// <summary>
/// Find the specified name in the index and load a time zone
/// definition. If the name is not found then return null.
/// </summary>
static TimeZone loadTimeZone(string x)
{
string name = x;
int slash = x.LastIndexOf('/');
if (slash > 0) name = name.Substring(slash+1);
// find index, which maps the file offset
// TODO: why doesn't BinarySearch work?
// int ix = Array.BinarySearch(indexNames, name);
int ix = -1;
for (int i=0; i<indexNames.Length; ++i)
if (name == indexNames[i]) { ix = i; break; }
if (ix < 0) return null;
// map full name
string fullName = name;
string prefix = prefixes[indexPrefixes[ix] & 0xff];
if (prefix.Length != 0) fullName = prefix + "/" + name;
if (slash > 0 && x != fullName) return null;
// create time zone instance
TimeZone tz = new TimeZone();
tz.m_name = name;
tz.m_fullName = fullName;
// read time zone definition from database file
FileStream f = dbFile.OpenRead();
DataReader d = new DataReader(f);
try
{
f.Seek(indexOffsets[ix], SeekOrigin.Begin);
int numRules = d.ReadUnsignedShort();
tz.rules = new Rule[numRules];
for (int i=0; i<numRules; ++i)
{
Rule r = tz.rules[i] = new Rule();
r.startYear = d.ReadUnsignedShort();
r.offset = d.ReadInt();
r.stdAbbr = d.ReadUTF();
r.dstOffset = d.ReadInt();
if (r.dstOffset == 0) continue;
r.dstAbbr = d.ReadUTF();
r.dstStart = loadDstTime(d);
r.dstEnd = loadDstTime(d);
if (i != 0 && tz.rules[i-1].startYear <= r.startYear)
throw new IOException("TimeZone rules not sorted: " + name);
}
}
finally
{
f.Close();
}
return tz;
}
//////////////////////////////////////////////////////////////////////////
// Database
//////////////////////////////////////////////////////////////////////////
//
// TimeZone database format:
//
// ftz
// {
// u8 magic ("fantz 02")
// utf summary
// u1 numPrefixes
// utf[] prefixes
// u2 numIndexItems
// indexItems[] // sorted by name
// {
// u1 prefix id
// utf name
// u4 fileOffset
// }
// timeZones[]
// {
// u2 numRules
// rules[]
// {
// u2 startYear
// i4 utcOffset (seconds)
// utf stdAbbr
// i4 dstOffset (seconds); if zero rest is skipped
// [
// utf dstAbbr
// dstTime dstStart
// dstTime dstEnd
// ]
// }
// }
//
// dstTime
// {
// u1 month
// u1 onMode 'd', 'l', '>', '<' (date, last, >=, and <=)
// u1 onWeekday (0-6)
// u1 onDay
// i4 atTime (seconds)
// u1 atMode 'w' , 's', 'u' (wall, standad, universal)
// }
//
// The timezone database is generated by the "/adm/buildtz.fan"
// script. Refer to the "zic.8.txt" source file the code
// distribution of the Olson database to further describe
// model of the original data.
//
/// <summary>
/// Load the name and file offset list from file into memory.
/// </summary>
static void loadIndex()
{
DataReader reader = new DataReader(new BufferedStream(dbFile.OpenRead()));
try
{
// check magic "fantz 02"
long magic = reader.ReadLong();
if (magic != 0x66616e747a203032L)
throw new IOException("Invalid magic 0x" + magic.ToString("X").ToLower());
reader.ReadUTF();
// load prefixes
int numPrefixes = reader.ReadByte();
prefixes = new string[numPrefixes];
for (int i=0; i<numPrefixes; ++i)
prefixes[i] = reader.ReadUTF();
// load the zones and verify in sort order
int num = reader.ReadUnsignedShort();
indexPrefixes = new byte[num];
indexNames = new string[num];
indexOffsets = new int[num];
for (int i=0; i<num; ++i)
{
indexPrefixes[i] = reader.ReadByte();
indexNames[i] = reader.ReadUTF();
indexOffsets[i] = reader.ReadInt();
if (i != 0 && String.Compare(indexNames[i-1], indexNames[i], StringComparison.Ordinal) >= 0)
throw new IOException("Index not sorted");
}
}
finally
{
reader.Close();
}
}